Vitrectomy for floaters?

Disability may justify surgery, but careful patient selection is essential

Google 'eye floaters' and plenty of promos for natural remedies and practices 'specialising' in surgical and laser floater procedures pop up. Clearly there's a market for treating anxious floater patients – and no shortage of dubious operators looking to cash in.

But in the world of real ophthalmology, is pars plana vitrectomy appropriate for managing patients with visually significant floaters? In an instant poll of several hundred ophthalmologists attending the Great Debates symposium at the 2010 American Academy of Ophthalmology annual meeting, 67 per cent voted 'No.'

Not really surprising given the risks of penetrating surgery, including retinal detachment, endophthalmitis and future cataracts. Hardly seems worth it to clear up a few pesky spots.

But then again…

The task of convincing this sceptical audience otherwise fell to David S Boyer MD, of Retina Vitreous Associates Medical Group, Los Angeles, US. He presented a nuanced argument that symptomatic vitreous floaters can be debilitating, and when they are, vitrectomy may be an appropriate option.

Dr Boyer acknowledged upfront that most vitreous floaters are benign and do not require treatment. But floaters can significantly reduce patients' functioning, and it may be hard to pick this up using standard tests or physical examinations.

'Patients complain they can't see, but they test 20/20 in our office. But when we take our standard Snellen visual acuity measurements they do not account for the speed at which someone reads or other aspects of visual disability that interfere with daily life. Subjective questionnaires such as the NEI VFQ-25 may show functional deficits, but this is not something we do routinely.'

He suggested that patients with floaters who hesitate between letters when reading the chart may be exhibiting a functional deficit, and should be investigated further.

'A lot of patients who have severe floaters can't drive. So ask, can they read street signs when driving? Read for extended periods? Use their computer like they did before the PVD?' Dr Boyer asked. Functional vision tests may also be appropriate.

For patients who do demonstrate ongoing disability, Dr Boyer believes that vitrectomy is preferable to NdYAG laser. Studies, including one by Stanley Chang MD and colleagues (Retina 2000; 20:591-6) have found vitrectomy leads to resolution or improvement of floater symptoms in nearly all eyes, while YAG laser improves symptoms in only 38 per cent of eyes, and actually makes the condition worse in nearly eight per cent (Eye 2002; 16. 21-26).

'Would you withhold cataract surgery if the cataract was visually disabling despite good Snellen VA, where under certain circumstances the patient can't drive? If they can't function I would offer the patient the ability to improve their quality of life by vitrectomy surgery,' Dr Boyer said.

Yes, but…

Arguing against was Stanley Chang MD, Edward Harkness Professor of Ophthalmology, Columbia University in New York, who co-authored one of the papers Dr Boyer cited. Published in 2000, this case series presentation involving six consecutive surgeries in five patients was the first peer-reviewed paper on the subject.

'I do believe there is disability associated with floaters, but it is relatively rare. We selected these patients very carefully. All had PVD and several had previous retinal surgery.'

All of the patients were also pseudophakic or aphakic, eliminating cataract risk. The results were good. All achieved corrected visual acuity of 20/40 or better, four had 20/25 or 20/20. No complications were observed. Significant functional improvements were demonstrated by VFQ-39 questionnaire, and all six patients reported a high degree of satisfaction.

So why did Dr Chang take the 'con' side? He cited a study (Schulz-Key S et al, Acta Ophthalmol 2009; 1) in which 73 eyes in 61 patients were evaluated in a retrospective non-randomised study that used a lower threshold for surgery. Forty-two per cent were phakic and four combined vitrectomy with phaco. At the end of follow-up, 60 per cent of phakic eyes required cataract extraction, and nearly seven per cent developed retinal detachments. As a result, satisfaction rates were lower, with 75 per cent reporting improvement in symptoms. Other research suggests that for patients with no PVD, retinal tear rates may be as high as 23 per cent after vitrectomy.

In many cases, floaters lessen with time, Dr Chang said. So he suggests patients wait at least a year before considering surgery. Also, in some cases symptoms are not consistent with opacities observed on slit lamp biomicroscopy.

'These patients seem obsessed with them and even if you operate they will not be happy because there will still be peripheral floaters they can see.'

Dr Boyer agreed that assessing patients is difficult and takes time.

'You do not want to see somebody and operate the next week. There are risks involved. But there are risks involved in everything we do. In cases where the floaters are really bothering the patient, he may be a candidate.'

Dr Chang concluded that he and Dr Boyer were 'really not that far apart about the need to be very careful about evaluating patients. Yes, there are some who deserve this surgery, but be very careful about patient selection.' He said that the evaluation of these patients remains based on their subjective symptoms, and that objective measures to determine who are surgical candidates are lacking.

And the audience? After the debate 62 per cent still voted 'No' – a five per cent shift toward vitrectomy for floaters, but not exactly a ringing endorsement.